vim-patch:9.1.1829: filetype: KerML and SysML files are not recognized (#36042)

Problem:  filetype: KerML and SysML files are not recognized
Solution: Detect *.kerml as kerml filetype, detect *.sysml as sysml
          filetype, include a kerml and sysml filetype plugin
          (Daumantas Kavolis)

closes: vim/vim#18476

b73ccf7ff0

Co-authored-by: Daumantas Kavolis <daumantas.kavolis@sensmetry.com>

runtime/ftplugin/kerml.vim

@@ -0,0 +1,23 @@
+" Vim filetype plugin
+" Language:         KerML
+" Author:           Daumantas Kavolis <daumantas.kavolis@sensmetry.com>
+" Last Change:      2025-10-03
+
+" Only do this when not done yet for this buffer
+if exists("b:did_ftplugin")
+  finish
+endif
+
+" Don't load another plugin for this buffer
+let b:did_ftplugin = 1
+
+" Set 'comments' to format dashed lists in comments.
+setlocal comments=sO:*\ -,mO:*\ \ ,exO:*/,s1://*,mb:*,ex:*/,:///,://
+setlocal commentstring=//*\ %s\ */
+
+" Set 'formatoptions' to break comment lines but not other lines,
+" and insert the comment leader when hitting <CR> or using "o"
+setlocal formatoptions-=t
+setlocal formatoptions+=croql
+
+let b:undo_ftplugin = 'setlocal comments< commentstring< formatoptions<'

runtime/ftplugin/sysml.vim

@@ -0,0 +1,12 @@
+" Vim filetype plugin
+" Language:         SysML
+" Author:           Daumantas Kavolis <daumantas.kavolis@sensmetry.com>
+" Last Change:      2025-10-03
+
+" Only do this when not done yet for this buffer
+if exists("b:did_ftplugin")
+  finish
+endif
+
+" Behaves mostly just like KerML, only differs by keywords
+runtime! ftplugin/kerml.vim

runtime/lua/vim/filetype.lua

@@ -672,6 +672,7 @@ local extension = {
   kl = 'karel',
   KL = 'karel',
   kdl = 'kdl',
+  kerml = 'kerml',
   kv = 'kivy',
   kix = 'kix',
   kts = 'kotlin',
@@ -1216,6 +1217,7 @@ local extension = {
   sys = detect.sys,
   Sys = detect.sys,
   SYS = detect.sys,
+  sysml = 'sysml',
   svh = 'systemverilog',
   sv = 'systemverilog',
   cmm = 'trace32',